Stick with fluid and tacks, every so often (4)
I believe the answer is:
flak
'stick' is the definition.
(I've seen this before)
'fluid and tacks every so often' is the wordplay.
'fluid' becomes 'fl' (eg in fl oz, fluid ounce).
'and' means one lot of letters go next to another.
'every so often' means one should take alternating letters.
The alternating letters of 'tacks' are 'ak'.
'fl'+'ak'='FLAK'
'with' is the link.
(Other definitions for flak that I've seen before include "Anti-aircraft fire - strong criticism" , "Burst of abuse" , "Severe criticism" , "that can bring down a plane" , "Anti-aircraft shells or adverse criticism" .)